qof_instance_get gchar* must be freed

A call to qof_instance_get expecting a gchar* receives a newly
allocated string which must be freed.

gnucash/gnome-utils/gnc-tree-view-account.c

@@ -1866,9 +1866,10 @@ account_cell_property_data_func (GtkTreeViewColumn *tree_column,
     account = gnc_tree_view_account_get_account_from_iter(s_model, s_iter);
     qof_instance_get (QOF_INSTANCE (account), key, &string, NULL);
     if (string == NULL)
-        string = "";
+        string = g_strdup ("");
 
     g_object_set (G_OBJECT (cell), "text", string, "xalign", 0.0, NULL);
+    g_free (string);
 
     view = g_object_get_data(G_OBJECT(tree_column), "tree-view");
 

gnucash/gnome/gnc-plugin-page-report.c

@@ -1965,13 +1965,16 @@ gnc_plugin_page_report_exportpdf_cb( GtkAction *action, GncPluginPageReport *rep
             // Yes. In the kvp, look up the key for the Export-PDF output
             // directory. If it exists, prepend this to the job name so that
             // we can export to PDF.
-	    if (dirname && g_file_test(dirname,
-				       G_FILE_TEST_EXISTS | G_FILE_TEST_IS_DIR))
-	    {
-		gchar *tmp = g_build_filename(dirname, job_name, NULL);
-		g_free(job_name);
-		job_name = tmp;
-	    }
+            if (dirname)
+            {
+                if (g_file_test (dirname, G_FILE_TEST_EXISTS | G_FILE_TEST_IS_DIR))
+                {
+                    gchar *tmp = g_build_filename (dirname, job_name, NULL);
+                    g_free (job_name);
+                    job_name = tmp;
+                }
+                g_free (dirname);
+            }
         }
     }
 

libgnucash/engine/qofbook.cpp

@@ -1032,13 +1032,11 @@ qof_book_get_default_gain_loss_acct_guid (QofBook *book)
 gboolean
 qof_book_use_trading_accounts (const QofBook *book)
 {
-    const char *opt = NULL;
-    qof_instance_get (QOF_INSTANCE (book),
-              "trading-accts", &opt,
-              NULL);
-    if (opt && opt[0] == 't' && opt[1] == 0)
-        return TRUE;
-    return FALSE;
+    char *opt = nullptr;
+    qof_instance_get (QOF_INSTANCE (book), "trading-accts", &opt, nullptr);
+    auto retval = (opt && opt[0] == 't' && opt[1] == 0);
+    g_free (opt);
+    return retval;
 }
 
 /* Returns TRUE if this book uses split action field as the 'Num' field, FALSE